1. Field of the Invention
The present invention relates to the geometrical configuration of woven three-dimensional structures, and more particularly to such structures which are adapted for use in high strength composite materials.
2. Description of the Prior Art
A wide variety of reinforced fiber or filament composite materials and structures are known in the art. Generally speaking, such structures consist of an array of fibers, filaments or rods embedded in a matrix-material which encases the fibers and fixes them into position. Any number of materials, including but not limited to glass, quartz, graphite, steel, asbestos and boron, may be used as fibers or filaments in such composite materials. Similarly, many materials, including plastics, ceramics and resins, to name just a few, may form the matrix-material.
A variety of woven structures are known. For example, U.S. Pat. No. 4,336,296 describes a three-dimensionally latticed flexible structure composite material suitable for absorbing repeatedly exerted external impacts. Similarly, U.S. Pat. No. 4,546,032 discloses a fiber reinforced composite structure exhibiting enhanced tailored anisotropic shear strength properties.
Additional reinforced composite structures which embody other characteristics and properties are also known. For example, U.S. Pat. No. 3,904,464 describes a process for producing, in billet form, a compact composite structure having inter-fiber frictionally based self-supporting three-dimensional integrity and enhanced structural strength properties. Also, structures involving non-mutually perpendicular elements and various net shapes, such as cylinders, cones and the like, as described in U.S. Pat. Nos. 4,379,798, 3,749,138 and 4,725,485, are well known. Further, structures allowing for joining of intersecting structural members, as in U.S. Pat. No. 4,715,560, are also known.
However, all of the prior art structures exhibit one or more of a number of problems and deficiencies. A principle deficiency is that none of the prior art structures, as more fully explained hereinbelow, exhibit a maximum degree of interweavement of fibers or filaments. Therefore, these fibers or filaments are not "interlocked" in all possible places. Consequently, all of the prior art structures exhibit various planes or axes of mechanical and structural weakness; i.e., they do not exhibit isotropic mechanical and structural strength characteristics. Moreover, because of this lack of mechanical strength isotropy, all of the prior art structures suffer from a need to be properly oriented when used in given applications. This creates problems for end users who must not only solve the problem of how to properly orient a material in a given application, but also contend with the various mechanical and structural weaknesses that exist in the structures' non-maximum strength planes and axes.
An additional problem with the prior art structures is that, because of their lack of maximum degree of fiber interweavement, they cannot provide the maximal degree of rigidity of which their fibers or filaments are capable.
A further problem is that, because their filaments are not maximally interlocked, none of the prior art structures can exist as a "self-maintaining" structure, absent an encasing matrix-material and a maximal degree of compactness.